Iran is a pluralistic society. Persians are the largest ethnic group in Iran, though many are actually of mixed ancestry. The population of the country has important Turkic elements (e.g., Azeris) and Arabs predominate in the southwest. In addition, Iran’s population includes Kurds, Balochi, Bakhtyari, Lurs, and other smaller minorities, such as Armenians, Assyrians, Jews, and Brahuis (or Brohi). The 1979 Islamic Revolution and the 1980-88 Iran-Iraq war transformed Iran's class structure politically, socially, and economically. During this period, Shi’a clerics took a more dominant position in politics and nearly all aspects of Iranian life, both urban and rural.

Most Iranians are Muslims; 89% belong to the Shi'a branch of Islam, the official state religion, while about 9% belong to the Sunni branch. Non-Muslim minorities include Zoroastrians, Jews, Baha'is, and Christians. The December 1979 Iranian constitution defines the political, economic, and social order of the Islamic Republic. The document establishes Shi'a Islam of the Twelver (Jaafari) sect as Iran's official religion. Sunni Islam, Zoroastrianism, Judaism, and Christianity are the only other recognized, legal minority religions. The country is governed by secular and religious leaders through governing bodies, whose duties often overlap. The Supreme Leader holds power for life unless removed by the Assembly of Experts. He has final say on all domestic, foreign, and security policies for Iran, though he establishes and supervises those policies in consultation with other bodies, including the National Security Council and the Expediency Council. The Supreme Leader is the final arbiter on nearly all disputes among the various branches of government, although the Expediency Council is charged with resolving disputes between the Majles and the Guardian Council. The Supreme Leader appoints officials to key positions including the head of judiciary and the Council of Guardians. He has the power to remove the president and is commander-in-chief of the armed forces.

On December 20, 2010 a magnitude 6.5 earthquake hit the Southeastern region of Iran (100km SE of the city of Bam; 1080km SE of the capital, Tehran). For more information about earthquakes, visit the U.S. Geological Survey's Earthquake Hazards Program.

U.S. State Department Background Notes; CIA World Factbook; U.S. Geological Survey, 7/2010; 12/2010